1. Field of the Invention
The present invention relates to a portable electronic device such as a multifunctional IC card which incorporates, e.g., a CPU, a data memory, a built-in battery, and the like, and is solely used to provide an electronic calculator function, a time display function, or the like, or is inserted in a terminal in use.
2. Description of the Related Art
Conventionally, multifunctional IC cards have been developed. An IC card of this type incorporates a CPU (control element), a data memory, and the like, has a keyboard, a display unit, and the like, and is solely used to provide an electronic calculator function, a time display function, or the like, or is inserted in a terminal in use.
An IC card of this type has an oscillator for always outputting a stable clock signal.
When a voltage from a built-in battery is directly supplied to the oscillator, current consumption of the oscillator is large, and a service life of the built-in battery is shortened.
When a power supply voltage having a low voltage value (1/2 voltage) is generated based on an output from the internal oscillator using a voltage generator, and this low voltage is supplied to the internal oscillator, current consumption can be suppressed, and the service life of the built-in battery can be prolonged.
In this arrangement, however, when an IC card is accidentally dropped, or some shock acts on the IC card, a vibrator of the oscillator may be brought into contact with a case of the IC card, and its vibration may be stopped. In this case, the function of the voltage generator is stopped, and supply of a power supply voltage is stopped. As a result, the function of the IC card is stopped.